Mediki
Free T3 blood test: what your result means
Free T3 measures the unbound active fraction of T3 available to tissues.
- Category
- Thyroid
- Standard unit
- pmol/L
- Reported in
- pmol/L, ng/L, pg/mL, pg/dL, pg%, pg/100mL and more
What does high free T3 mean?
Higher values may suggest increased active thyroid hormone effect. What counts as high depends on the reference range printed on your lab report, because ranges differ between laboratories.
What does low free T3 mean?
Lower values may suggest reduced active thyroid hormone availability. What counts as low depends on the reference range printed on your lab report, because ranges differ between laboratories.
Free T3 units and conversion
Mediki shows free T3 in pmol/L. Labs may report it in other units; Mediki converts them automatically so results from different labs line up on one chart.
| Unit on your report | Convert to pmol/L | Convert back |
|---|---|---|
| ng/L, pg/mL | 1 ng/L = 1.536 pmol/L | 1 pmol/L = 0.651 ng/L |
| pg/dL, pg%, pg/100mL | 1 pg/dL = 0.01536 pmol/L | 1 pmol/L = 65.1 pg/dL |
| ng/dL | 1 ng/dL = 15.36 pmol/L | 1 pmol/L = 0.0651 ng/dL |
Convert a value from your report with the blood test unit converter.
Why track free T3 over time?
A single free T3 result is a snapshot. Comparing it with your earlier tests shows whether a value is stable, slowly drifting, or responding to a change in treatment or lifestyle, which is often more useful than one number on its own.
Read our guide on how to read blood test results to understand reference ranges, flags and units.
Following free T3 as part of a panel? See the thyroid test tracker.
Track your free T3 results in one chart
Upload your lab reports and Mediki plots every free T3 result against its reference range. Your first 15 pages are free.
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Medical disclaimer: This page is general information, not medical advice. Reference ranges differ between laboratories, and only a doctor can interpret your results in the context of your health.